This invention relates to a high speed, photographic quality printer. More particularly, the invention relates to an apparatus for separating a sheet of print media from a stack of sheets, the sheets being porous.
The applicant has developed various printheads which provide high speed, photographic quality printing. The printheads comprise ink jet nozzles arranged in a close packed array. To provide the photographic quality printing, the nozzles are so arranged so as to provide a resolution of up to 1600 dots per inch (dpi).
The ink jet nozzles are formed using microelectromechanical systems (MEMS) technology. The use of MEMS technology results in very high speed printing capabilities where pages can be printed at a rate of up to 2 pages per second (for double-sided printing). To facilitate such high speed printing, it is important, firstly, that the paper or print media fed to the printing station of the printer is accurately aligned and capable of the required feed rate with as little likelihood as possible of paper jams or the like occurring. Secondly, the paper must be able to be fed to the printing station at a rate sufficient to use the high speed printing capabilities of the printing station to its fullest extent.
According to the invention, there is provided an apparatus for separating a sheet of print media from a stack of sheets, the sheets of the stack being porous and the apparatus including:
a sheet conveying means for conveying a topmost sheet of print media, which has been separated from the stack, to a printing station of a printer;
a separating means, associated with the sheet conveying means for separating the sheet of print media from the stack, the separating means including a fluid delivery means for blowing fluid on to a top surface of the stack for effecting separation of the topmost sheet of print media from the stack; and
a capturing means, carried by the sheet conveying means, for capturing at least a part of said topmost sheet and for facilitating conveyance of said topmost sheet by the sheet conveying means to the printing station.
The sheet conveying means may comprise a picker assembly for picking the topmost sheet from the stack. The picker assembly may comprise an elongate element in the form of a bar or tube and a plurality of displacement assistance means for assisting in displacement of the topmost sheet from the stack, the displacement assistance means being arranged at spaced intervals along a length of the elongate element.
The elongate element may define a plurality of fluid ports and each displacement assistance means may comprise a footprint-defining portion surrounding one of the ports and depending from the elongate element. More particularly, each displacement assistance means may be in the form of a pad or disc which depends from the elongate element towards the stack, in use. Each pad may depend from a hollow stalk which is received in one of the fluid ports of the elongate element. The stalk may define a passage.
The fluid delivery means may comprise a plurality of fluid supply conduits, each conduit being in fluid communication with one of the fluid ports of the elongate element, only certain of the fluid ports having fluid supply conduits associated with them with a remainder of the fluid ports not being in fluid communication with the fluid supply conduits.
The fluid supply conduits may be connected to, and communicate with, a fluid supply manifold.
The capturing means may be a fluid suction arrangement, the capturing means comprising a plurality of flu id suction conduits, each fluid suction conduit being in fluid communication with one of the remainder of the fluid ports of the elongate element.
The fluid suction conduits may be connected to, and communicate with, a fluid extraction manifold.
The picker assembly is operable to lift the topmost sheet from the stack and to feed it to the printing station. A pair of pinch rollers may be arranged at an input to the printing station. In a preferred embodiment, the bar of the picker assembly is mounted on a pair of spaced swing arms and pivots relative to the swing arms. The swing arms, in turn, are fixedly mounted on an axle which is rotatably supported on the printer. Accordingly, to facilitate movement of the bar of the picker assembly, the fluid supply conduits and the fluid suction conduits may be in the form of flexible hoses.
The apparatus may comprise a fluid supply means for supplying a fluid to the fluid supply manifold for supply to the fluid supply conduits and a fluid extraction means for extracting fluid from the fluid extraction manifold to create a suction effect in the fluid suction conduits. The apparatus may further comprise a drive means for driving the fluid supply means and the fluid extraction means. The fluid supply means and the fluid extraction means may each be in the form of an air pump and extraction pump, respectively.
The drive means may be a drive motor. The air pump may be mounted on a first output shaft of the drive motor with the extraction pump being mounted on an opposed, second output shaft of the drive motor.
The apparatus may further comprise a control means for controlling supply of fluid to the fluid supply manifold and extraction of fluid from the fluid extraction manifold. The control means may comprise a valve arranged in each of the fluid supply manifold and the fluid extraction manifold. Preferably, each valve is electromagnetically operated. More particularly, each valve may be in the form of a solenoid valve arranged in an inlet opening of the fluid supply manifold and an outlet opening of the fluid suction manifold.